## Engineering Physics - Jun 2015

### First Year Engineering (Semester 2)

TOTAL MARKS: 50

TOTAL TIME: 2 HOURS
(1) Solve Q.1 or Q.2, Q.3 or Q.4, Q.5 or Q.6, Q.7 or Q.8

(2) Assume suitable data, if necessary.

### Answer any one question from Q1 and Q2

**1 (a)** Derive an equation for path difference in reflected light when monochromatic light falls on the uniform thickness film and hence state the conditions for maxima and minima.(6 marks)
**1 (b)** State any two factors affecting the acoustics of a hall and explain in brief remedies on that.(3 marks)
**1 (c)** Calculate the reverberation time of hall with volume of 1500 m^{3} and total absorption is equivalent to 100 m^{2} Sabine.(3 marks)
**2 (a)** What is Piezoelectric effect? Draw a neat diagram and explain Piezoelectric generator for the production of ultrasonic waves.(6 marks)
**2 (c)** A laser light of wavelength 6328 A.U. falls normally on a
grating which is 2 cm long. The first order spectrum is observed at an angle of 20°. Find the total number of slits on grating.(3 marks)

### Answer any one question from Q3 and Q4

**3 (a)** Explain with neat labelled diagram construction and working
of Ruby laser.(6 marks)
**3 (b)** What is Fermi level? Show the position of Fermi level
in P-type semiconductor at temperature T = 0 K and T > 0 K.(3 marks)
**3 (c)** Calculate the number of acceptors to be added to a germanium sample to obtain the resistivity of 10 Ω cm. (μ=1700 cm^{2}/V sec.).(3 marks)
**4 (a)** What is Hall effect ? Derive the equation of Hall voltage.(6 marks)
**4 (b)** State and prove Law of Malus.(6 marks)
**4 (c)** A retardation plate of thickness 2.275×10^{-3} cm is cut with its faces parallel to optic axis. If the emergent beam of light is elliptically polarized. Find the wavelength of monochromatic light made incident normally on the plate. Given that, μ_{0}=1.586 μ_{e}=1.592.(3 marks)

### Answer any one question from Q5 and Q6

**5 (a)** State and explain Heisenberg's Uncertainty principle. Illustrate the same with electron diffraction at a single slit.(6 marks)
**5 (b)** What is wave functionψ? Give the physical significance of it.(4 marks)
**5 (c)** An electron is trapped in a rigid box of width 2 A.U. Find its lowest energy in eV.(3 marks)
**6 (a)** Deduce Schroedinger's time independent wave equation.(6 marks)
**6 (b)** Define phase velocity and prove that it is always greater than velocity of light.(4 marks)
**6 (c)** Calculate the de Broglie wavelength of proton when it is accelerated by potential difference of 10 kV.(3 marks)

### Answer any one question from Q7 and Q8

**7 (a)** State and explain Meissner effect and hence show that superconductivity is influenced by perfect diamagnetism.(6 marks)
**7 (b)** Explain how colloids are synthesized by the chemical route.(4 marks)
**7 (c)** Discuss applications of nanotechnology in medical field.(3 marks)
**8 (a)** Explain any two properties of nanoparticle.(6 marks)
**8 (b)** Distinguish between type-I and type-II superconductors.(4 marks)
**8 (c)** State any six applications of superconductivity.(3 marks)